Copper electrodeposition is used extensively in a variety of industrial applications including electroforming, electrorefining, manufacture of copper powder and electroplating. In electrorefining, relatively impure copper is generally dissolved from a consumable copper electrode and plated out in relatively pure form on a cathode. Electroforming is also extensively done in industry to produce various copper articles such as, electrotypes, phonograph records, band instruments, heat exchangers, reflectors, etc.
Copper electroplating is used in the production of many electrical devices and circuits. In many such applications, particularly in the production of circuit boards for electronic circuits, a copper electroplating process is used with nonconsumable electrodes. Such processes are more versatile than those using consumable electrodes, permit higher plating speeds, better control of the bath composition, require smaller apparatus size and generally yield copper layers with excellent physical properties. Particularly advantageous is the fact that the anode does not change size (i.e., cell geometry remains fixed) so that more uniform plating results are obtained. In addition, the copper salts used to provide the source of copper are often available as products of etching procedures associated with the production of copper plated devices. For example, in the production of circuit boards, a copper layer is put down over the entire surface of an insulating substrate and part of the copper etched off to produce the circuit board of interest.
Copper plating is used extensively in a variety of manufacturing procedures. It is used to prevent corrosion on various surfaces (i.e., iron surfaces), as a binding layer for additional metal layers, to increase electrical or thermal conductivity and to provide conducting paths in many electrical applications. Indeed, such of the recent increase in the activity in copper electroplating is in the manufacture of electrical devices, such as circuit boards, integrated circuits, electrical contact surfaces, etc.
Particularly important in any electroplating process is the stability and lifetime of the electroplating bath. Many electroplating baths contain additives which improve various aspects of the plating process. In particular, additives are used to improve the brightness of the copper plating, the physical properties of the plated copper particularly with respect to ductility and the micro-throwing power as well as macro-throwing power of the plating bath. Increased stability of these additives leads to longer lifetimes for the electroplating bath which is economically very important. For example, frequent replacement of the bath interrupts the copper plating operation which reduces product yield and requires replacement of the chemicals in the new bath as well as disposal of the chemicals in the old bath.